Adjustable reactance line



Oct. 4, 1949. l. KARMIN 2,

ADJUSTABLE REACTANCE LINE Filed July 24, 1944 s Sheets-Sheet 1 l- Mil M, '5'! INVENTOR. x? w/ve AA/RMl/V Mam;

ATTUHNE'Y Oct. 4, 1949..

Filed July 24, 1944 l. KARMIN ADJUSTABLE REACTANGE LINE 5 Sheets-Shet 2 6 6 7 r- 2 4 2 4 .2-: F g I I I 2 2 INVENTOR.

I 5 BY ATTORNEY Thisinvention relates Patented Oct. 4,

. U I D" STATE PATEN E I 2,483,419 j V T ADJUs'rABL RE cTAnoE 'Irving Karmin, Brooklyn, N. Y., assignor to Federal Telephoneand Radio Corporation, New

York, N.. Y., aw corporation ;of Delaware 1 Application July a4, 194 Serial No. 546,379

I to line sections wherein the reactance of theline-can be varied, in accordance with the frequencies desired, bya shorting device adjustably'mounted within'the line section and adjusted from without along the longitudinal length thereof;

Where coaxial line sections are employed in high frequency circuits for both the tuning of the circuits-for'desired frequencies and for the transmission of high voltage currents, it is of utmost importance to have the impedance characteristics of theline identical throughout, and of still greater importance-to prevent the passage of the high voltagesfrom one conductor to the other when tuning the line for a desired resonant frequency.; T '1 It is also often necessary, where the longitudinal working length o'f-the coaxial line is confined to its actual length because of the restriction of space, to providethe line section with a longitudinal slot or opening for adjusting the shorting device within thelinet'o varythe fective length of the line'section.

This longitudinal slot or opening in the outer conductor changes somewhat the characteristic impedance of the line and is found to be quite unsatisfactory. 1 One of the objects of my inventionis to construct a tunable line section-having an outer --c0nductor: provided witha longitudinal slot or opening and still havesubstantially the same impedance characteristic as .a similar closed. co-

- axialline..

Another object of. my invent on isto provldea shorting device whichwilltoperate in con unctionwith: my particular types of coaxial line.

Afurther ,object'of my invention is to prov de a shorting device which will. pass the high irequency currentsand yet prevent the. passage of direct current fromone conductor of the coaxial line to the other.

In carrying out Inyinv e ntior prefer to construct the outer conductor with alongitudinal opening wide enough to insert 'a'nd'withdraw the shorting device so that it will be unnecessary to slide the shortin gdevi'ce the whole lengthof the line when making the desiredv adjustments.

When it is desired to make a radical adjustment in the length of the line it will only be necessary tolift the shorting device out of the coaxial line through the slot or opening and carry it to the'approximate distance for th e new adjustment and then insert it 1 through the slot or opening into the coaxial line, from which point the short- 'ing device can be moved longitudinally forwardly or rearwardly until the desired res'onant frequency has been reached.

Further objectswill become apparent, reference being had to the accompanying description and claims read together with the drawings in which:

Fig. 1 is an end elevation view of one embodiment of my invention provided with one form of shorting device applied to one form of line section;

Fig. 2 is a side elevational view of Fig. 1; with part of the outer conductor broken away to more readily show the shorting device;

Fig. 3 is a top plan view of the line section and shorting device shown in Figs. 1 and 2;

' Fig. 4 is a bottom plan 'view of the shorting device; 1 T Fig. 5 is an end elevational view of another embodiment of my invention showing the same shorting device shown inFigs. 1, 2 and 3cooperating with a difierent form of line section; Fig.- 6 is an end elevational viewof a further embodiment of a shorting device in accordance with my invention for -use in conjunction with the line sections shown in Figs. 1=to 5 inclusive; Fig. 7 is a side 'ele'vational view of the shorting device shown in Fig. 6; and

Fig. 8 is'a bottom plan viewof the'shorting deviceshown in Figs. 6 and "7. I

Referring now to Figs. 1, '2, 3and1 i wherein a line "section I is shown'composed of an' irmer conductor 2, and an outerconductor3 the "lower .portion of which is spaced substantially'equally from the inner-conductor Zfand provided with upwardly extending side walls 4, 4- to define an opening 5 in the outer conductor thereof.

The sidewalls 4,' 4 also extending. longitudinally of the line section I, extend upwardly in a :rsubstantially parallel relation to one another .from approximately the transverse center line of the "line section and are sufficientlyextended -to maintain substantially the same impedance characteristics as a similar closed coaxi al'line, that is, a coaxial-line which has an inner conductor of the same dimensions as the corresponding' conductor of line section I and a completely closed substantially circular outer conductor having an inner diameter equal to the spacing of'the inner faces of the extended side walls.

Slidably mounted within the line section I a shorting device 5' provided with a pair of resilient conductive members J and 8 adapted to respectively-engage the inner opposite side walls 4, 4 of-the outer'conductor 3 and the outerop- "posite side walls ofth'e inner conductor 2. A1- though the 'resilient conductive member" 8 is primarily adapted for contacting the inner conductor electrically, it is also adapted to straddle the conductor and be longitudinally adjusted along the length of the line section. The conductive member 1 serves not only to electrically contact the outer conductor but also to maintain the entire shorting device centralized between the parallel side walls 4,1 of conductor 3.

Referring-now to Figs 4 wherein the shorting device 6 is shown on an enlarged scale so that a better understanding can be had of its construction and the employment thereof, .it will ..be seen that the conductive members 1 and 8 are as sembled as a unitary structure. =.'I he, c0ndl1ci3ive member 7 being composedofa pair rot-outwardly, bowed members I0, l have their-free ends posi-' tioned oppositely one another longitudinally of the supporting element 9 (Figs; 1; '2 and 3) and their other ends connected together transversely thereof in spaced-apart relation thereto. The free end portions of theparallel side flanges ,of each element it) is proyidedwitha pluralitypf longitudinal slits !l,,to render the conductor contacting end portions more flexible. ,The ,conductive members 8, composedofapairof flatmcon- .ductive elements 112, l2 positioned transversely of the supporting ,element ,9, are interposed 5,111 spaced-apart relation: between the members 18, Ill. Between the interconnected ends of the members ill, I!) and the members i2, i2 is a sheet of insulating material l3, l3 separating these members in capacitive relation. IntfiIDQsed between the members l2,. l2 are aplurality pf capacitor plates l4 and |5 also separated by sheets of insulating material. Ihegcapacitor plates I are connected together with the members; 10,-,18 whereas the capacitor plates l5 are connected together with the members l2,l2. From the foreigoing description it can be readily seen that the .members lfl, lflcare in capacitive relation to the conductive members l2, l2 and when employed in the line section will pass high frequencies. currents and prevent the passage of direct currents from one conductor to the other.

'The conductive members I2, I2 are providedwith depending extensions l6, -l$,bifurcated at their lowerextremities to provide the extensions with openings I! by whichathe shorting .device .6 can be mounted upon andstraddle theinner ,con- .ductor Z of the. coaxial line I. Each leg'of the bifurcation is further provided with conductive contacting portions l8 bent longitudinally to the supporting element 9 andbowed inwardly to contact. the outer opposite side walls of the inner conductor-23nd further provided with longitudinal slits; l9 to nendei -the contacting portions I! more flexible. V V

.;From the foregoing. description of the coaxial line! and the shorting devicefi, it can readily be seen that the shortingdevice can easilybe ill- 1 .serted,into the coaxial line section; through the longitudinal slot ort-opening for the purposes of tuningv the-line to a desired' frequency.- Upon inserting the shorting device through the open- ..ing,the upper edge of opening I 1 of the bifurcated ...extensions-will rest upon, andthe legs thereof will straddle, the inner conductor 2 While:- the bowed conductor-contacting portions will enga e the. Outer opposite side walls to position vthe short- ,ing-device centrallytof the line section, whereas? r therbowed ends ofthe conductive members 10', J0 will prevent misalignment' of the shorting device fi whenadjusted longitudinally along. the length of the line section. -It can also be seen that'the shorting member can-be withdrawn at any time and readjusted at a difierent point along the line without sliding it along the conductors, thus reducing the wear and tear of both the shorting device 6 and the conductors 2 and 3 of the line 6 section.

Mounted upon the upper portion of the supporting element 9 is an insulated handle with which adjustment of the shorting device can be made. 7 1." '1

1 Referring now to Fig. 5 the line section I is ..-substantially silimar to line I previously described. V However the ,inner conductor 2 is substantially rectangular in form and, the outer conductor 3' .is,sub .tantia .lv,phannel shaped and spaced sub- .ls stantiallygequallycfrom the inner conductor at the lowerportioni thereof. The parallel side walls Agjfare sufiiciently extended from the base of the (spanner-to maintain substantially the same impedance characteristics as a similar closed 00- 2o axial line. The side walls 4, 4' define an opening {51in t equiereq asiuq p th aus iw a ph i se sh win s i e sli wn n..F g t taup .inseried aa .sliclaie re eat 1 PM; th in scgn lusz rli i stb tsam man r s fi ib in cgnee iqaniih il e -4- Referring now to;E i gs ;6,;7 and;8 a slightly imqaifle -.f0.r lo sh riilla ev e 12 b how .s giunei qn wit t e-il lel i is that other fprmspf line s ion maybe used as an d esired. "Ifhis shortingdevlce 2| provided with ca pair of tbshaped: conductiye.. nembers 22 and Z neste Pn,.. ihinihQI I fl 'iri s e -em -relation and secured to a handle 24-;for longitudiaqnsae t ith we. i i n c ax ing I a v V The base of the inner U;shaped,,member.22 posi ionedtr i syfi fi r .Q th l pee l li i P vis t Witl a .e ie ide ans s h n' s o wh h ar xtended longi udinally P th'e' Hamsters? mbases: top f0 d i wa ali vi uzizv i commiei tacting. portions 25 adapted; to. engage the outer oppositeside walls of the inner oonduotpr; 2'. The outer U-shapedmemberidis .provided at the ends of its parallel side flangesiwith longitudinal zexten'sions'i2d bowed, outwardly to engage the sinner opposite side; walls 01. the outer g conductor 3'. These bowed ends 25 and 2'6 mayabe provided with a plurality'ofllongitudinal slits.2'l to render them more' flxiblel interposed b.etween.,and connectedtoQthe side flang'es-of, the; U-shaped membe s 2'2 and 23'are a pair' of condensers! and- 2s coupling the condiictive membersin capa c i tive relation for the passage of highfrequency currents when'a djusted within thelline section.

It'can readily be seen that the shorting-device shown in F 'igsf 'd, 7 and 8', although somewhat diife ent in-construction will have the same useful pm ion as theshorting device shown in Fi s. 1, 12, 3,} and and the'same operational functions for shorting this line' section can' be performed in exactly the same manner as'des c'ribd Heredia bovegfor the shorting deviceI' ,,While I have shown andtdescribed two' forms 659i line sectionsandtwo lforn is of shorting elements to .be empl yed herewith, I realize that many mqrfi yai'iations in construction in both the ii i -t v e a d he short ng eyi eand er pplications thereof are, possible withou t departing from the spiritand scope: of my invention. It is to be .understoo'd,}however; that the forms herein 1 shown a and "described; are only. illustrations of v nt n-i an hel lnot b c n t mitationv of the sco'pe ofg 'my at pn' asls ip lth i h o goi mie t andihee a ae l ltie I claim:

1. A reactance line section comprising inner and outer conductors, said outer conductor including a semi-circular portion spaced substantially equally from said inner conductor and side walls mounted on the edges of said semi-circular portion and normal thereto and spaced apart a distance equal to the diameter of said semi-circular portion for providing a reactance line section with an opening along the length and a characteristic impedance substantially the same as a completely closed coaxial line section having the spacing existing between said inner conductor and semi-circular portion.

2. A variable reactance device according to claim 1 in which said outer conductor includes a circular portion of the same diameter as said semi-circular portion and ooaxially about a portion of said inner conductor and connected to said semi-circular portion.

3. A variable reactance device according to claim 1 further including shorting means insertable between said side walls to couple together said inner and outer conductors, said shorting means being adjustable longitudinally of said line section through the opening formed between said side walls.

4. A shorting device for electrically coupling to gether the inner and outer conductors of a line section, wherein the outer conductor is provided with a longitudinal opening defined by laterally extending side walls, comprising a shorting element including a first and second resilient conductive member capacitatively coupled together and securely mounted thereon, said shorting de- 35 vice capable of being inserted through and withdrawn from said opening to adjustably mount said shorting device upon said inner conductor within said line, said first conductive member engaging the inner opposite side walls of said outer conductor and said second conductive member engaging the outer opposite side walls of said inner conductor, and means accessible through said opening for adjusting said shorting device longitudinally along the length of said line section to vary the reactances thereof.

5. A shorting device according to claim 4, wherein said first conductive member is further provided with resilient parallel side flanges engaging the inner opposite side walls of said outer conductor and said second conductive member is further provided with downwardly extending bifurcated portions at its extended end for movably mounting said shorting element upon said inner conductor, the legs of said bifurcated end portion being provided with resilient conductor-engaging portions bent longitudinally to said line and adapted to engage the outer opposite side walls of said inner conductor.

6. A shorting device for electrically coupling together the inner and outer conductors of a line section wherein said outer conductor is provided with alongitudinal opening defined by laterally extending side walls, comprising a shorting element having a first pair and a second pair of conduc- 65 2,379,047

tive members, said first pair of conductive members being substantially U-shaped in cross-section and oppositely disposed in spaced-apart relation from one another, the resilient parallel sides 5 of said first pair of members adapted to engage the inner lateral side walls of said outer conductor longitudinally thereof, said second pair of conductive members being spaced capacitatively apart from each other and interposed in 10' capacitive relation to said U-shaped conductive members, said second pair of conductive members being provided with downwardly extending bifurcated portions at their extended ends to provide means for movably mounting said shorting 15 device upon said inner conductor, the legs of said bifurcated end portions being provided with resilient conductor-engaging portions bent oppositely one another and longitudinally to said line and adapted to engage the outer lateral side walls of said inner conductor, the capacitatively coupled conductive members being securely mounted on said shorting element for insertion through and withdrawal from said opening and for longitudinal adjustment along said line section to vary a the reactance thereof.

'7. A shorting device for electrically coupling together the inner and outer conductors of a line section wherein said outer conductor is provided with a longitudinal opening defined by laterally extending side Walls, comprising a shorting element having a pair of substantially U-shaped conductive members nested in spaced-apart relation, one within the other, and positioned within said line above and surrounding the greater portion of said inner conductor, the inner of said pair of U-shaped conductive members being provided with inwardly curved extensions on the ends of the parallel side thereof and engaging the outer opposite sides of said inner conductor 40 longitudinally thereof, the outer of said pair of 5 capacitive means interconnected between the parallel sides of said pair of U-shaped conductive members whereby said inner and outer conductors of said line are capacitatively coupled, and means accessible through said opening for lon- 5o gitudinal adjustment of said shorting device along the length of said line to vary the reactance thereof.

IRVING KARMIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS m Number Name Date 2,203,481 Zottu June 4, 1940 2,253,503 Bowen Aug. 26, 1941 2,306,282 Samuel Dec. 22, 1942 2,342,897 Goldstine Feb. 29, 1944 Thomas June 26, 1945 

